With Walton gone, the Detroit Lions still have Marcus Robertson, who was hired as a defensive assistant/secondary coach prior to last season. Schwartz can elect to have Robertson solely coach Detroit's secondary or hire another coach.

Robertson previously coached under Schwartz when both men were at the Tennessee Titans. He was the team's assistant secondary coach from 2007 to 2008 before serving as their secondary coach from 2009 to 2011.

Regardless of Schwartz's decision, the Lions have plenty of holes to fill in their secondary.

Detroit safety Louis Delmas, cornerback Jacob Lacey, cornerback Chris Houston and cornerback Drayton Florence will become unrestricted free agents this offseason. Lions safety Amari Spievey is a restricted free agent, but has a history of concussions in his short NFL career.

In addition, second-year cornerbacks Bill Bentley (shoulder) and Chris Greenwood (abdomen) are recovering from major injuries sustained last season.